In Experiment 1 participants gave 3 successive free recalls of items learned either individually or in pairwise collaboration. The first and third recalls were performed individually, the second alone or in collaboration. Collaborative recall led to an inhibitory effect after individual learning but not after collaborative learning, in which partners had similar retrieval strategies. Consistent with a retrieval locus for collaborative inhibition, non-recalled items reappeared in subsequent individual recall. Experiment 2 showed that collaborative inhibition was eliminated when a separate retrieval cue was given for each item. Experiments 2 and 3 also showed that when participants learned items in the same order, their retrieval strategies were more similar and they showed less collaborative inhibition. It is concluded that mutual interference in collaborative recall is due to the mutual disruption of individual retrieval strategies.